Trip-valve for air-brakes.



E. H. DEWSON.

TRIP VALVE FOR AIR BRAKES, APPLICATION FILED APR.6,19II.

Patented Jan. 18. 1916 IIIH'I'HIHHII WITNESSES INVENTOR Att'y.

a d lllfii reserve one.

EDWARD H. TEEW$DN, GI" NEW YGBK, IN. 2., ASSIGNfiI-t T0 THE WESTINGHOUSE A B'JItfiEE canteens, G1? IEIZlPTSBUEG-H, ZE'ENNSYLVANLQ, A GQRPSR-ATION 0B PENN- BYLVANUL TBIlZP VdLVE FOR AIR-BRAKES.

specification of Letters Eatent.

, Patented Jan. 1%, 1916.

To all whom it may concern:

Be it known that l, lflownno E. DEWSON, a citizen of the United States, residing at New York, in the county of New York and State of New York, haveinvented new and useful Improvements in Trip-Valves for Air- Brakes, of which the following is a specification.

This invention relates to air brakes for railway cars, and more particularly to trip valve devices therefor, adapted to he operated by contact devices along the track to open the train brake pipe and vent air therefrom to cause an applicationoi the automatic brakes when the train runs past a danger signal with which the track contact devices are connected.

In order that the brakes may be set with absolute certainty and full force at such times, it is necessary that the vent valve should be opened and remain fully open. for a suflicient period of time to allow a very material and rapid reduction of pressure-to take place in the train pipe, and it is also desirable that afterthis sullicient reduction has occurred, the vent valve should be automaticallyiclosed or reset, so that the brakes may be released and the train be ready to start again as soon as the danger is past.

Devices for this purpose have been here to'fore designed, as covered in my prior ap plication Serial No. 573,798, filed July 25, 1910, but the object of my present invention is to provide improv'ed meansfor this purpose, which will operate to positively hold the vent valve open until a certain reduction has been made in the train pipe pres sure which shall be sui'llcient to insure the brakes setting and remaining applied until the train is stopped.

With this object in view my improvement comprises a latch or locking mechanism governed by train pipe pressure and normally in position to prevent the closing of the vent valve after the same has been opened, but adapted to be automatically withdrawn from locking position when the train pipe pressure has diminished to a predetermined point, and then permit the vent valve to close.

Various forms of pneumatic latch or locking mechanism for this purpose may be devised, one of which is illustrated in the accompanying drawing, in which Figure l. is a vertical sectional view of a trip valve device embodying one form of my mechanism may be employed for opening the vent valve by the track contact device, such, for instance, as the plunger 8, having striking head 9, as indicated in Figs. 1 and '2, or operated by a double fulcrumed lever 10, as shown in Fig. 3.

As shown in Fig. 1, the locking mecha' nism comprises the latch member 13, com nected to the movable abutment or piston 11, which is normally held in locking position against the gasket 16, by the train pipe pressure but is adapted to be moved byspring 15, to its release or unlocking position, when the train pip e pressure is at or below a pre determined "point, as determined'by the tension of spring 15. The latch mechanism may be connected up to the vent valve device in any desired manner so as to hold the valve open after it has been actuated by the trip, but as here shown, the stem 4 is prosided with a beveled collar 12, for cooperating with the inclined edge'lof the latch to allow the same to yield as the stem of the valve is forced upward against its spring 14. Whenever the vent valve is thus opened by the upward thrust of the plunger 8,-the beveled collar passes above the latch 13, which immediately moves back to its normal locking position and prevents the descent of the stem and the closing of the vent valve as long as the train pipe pressure is sufficient to hold the latch piston seated against the tension of spring 15. In'this manner the vent valve is held wide open, causing a sudden and very material reduction in train pipe pressure, which insures the rapid and full application of the brakes.

. Vvhen the train pipe pressure has diminished to a certain low point, the spring 15,

acts to rnove the piston and latch to unlockglosltion in which the beveled collar 12 clears the edge of the latch and the spring 14: then returns the stem and vent to close the train pipe discharge. The mechanism s thus automatically, reset to its normal position'and the train pipe pressure may then be increased for releasing brakes in readiness .for the train to proceed.

As shown in Fig. 1, the latch 13 is rigidly connected with the piston '11, so that the train pipe pressure to which the pistonss subjected normally holds the latch in its locking position, and when the stemp l 1S thrust upward by the trip mechanism, the

' beveled collar 12, acting against the latch draws the piston momentarily away from'its seat ,on" gasket 16, as the collar passes above the latch. The piston and latch are then instantly forced back to locking position by the air pressure acting on the piston.

According to the modification shown in Fig. 4, the latch 13* 'is disconnected from the piston 11, so as to allow for an independent movement, and is provided with a light spring 18, for nermally holding the latch in its locking position against the collar 12 of the valve stem l. With this construction, the resistance to'the upward movement or the stem is greatly reduced as it is not neces sary to overcome the air pressure upon piston 11, which remains seated against its gasket, and the collar merely moves the latch outward against the light spring 13", which then returns the latch to locking position, and

I prevents the descent of the collar'lQ, and

valve stem 4. When the train pipe pressure has diminished to a certain point, the spring 15 acts to move "the piston 11 against the latch and actuates the same to its unlocking or release position, as before described, thereby permitting the closure of the vent valve. As the train pipe pressure is then increased for releasing and recharging the It will also be apparent that variouschanges and modifications as to the form and location of the latch mechanism may be made Without departing from the scope of my invention.

I claim as my invention and desire to secure by Letters Patent 1. A. trip valve device for air brakes, comprising a vent valve, trip mechanism for causing the opening'of the same to discharge air from the train pipe, and a latch device messes governed by train pipe pressure for pos1- tively preventing the closure of the valve until the train pipe pressure is reduced a given amount.

2. The combination of a train brake pipe,

'a vent valve for discharging air therefrom,

trip mechanism for opening said valve, and

'lochingmeans normally subject to the train pipe pressure for controlling the closing of valve open until the train pipe pressure is I reduced to a predetermined degree.

a. A trip valve device to; air brakes,

comprising a vent valve vfor discharging air from the train, pipe, trip mechanism for causing the opening of said valve, and a' yielding latch device governed by the train pipe pressure for preventing the closure of said valve until the train pipe pressure is reduced to a certain point.

5. A trip valve device for air brakes,

comprising a vent valve for controlling the discharge of air from the train. pipe, trip mechanism for causing the opening of said valve, a spring for closing said valve, and locking means governed by the train pipe pressure for holding said valve open until the train pipe pressure is'reduced a given amount. 7

GI A trip valve device for air brakes, comprising, a vent valve for controlling the discharge of air from the train pipe, trip mechanism for efiecting the opening of said valve, a latch for holding said valve open and a movable abutment normally subject ito grain pipe pressure for actuating the -atc 7, A trip valve device for air brakes, comprising a vent valve for controllingthe discharge of air from the train pipe, trip mechanism for effecting the-opening of said valve, means normally tending valve, a spring and a latch device governed by the opposing pressures of the train pipe and said spring for holding said valve open until the train pipe pressure is reduced a given amount. I

8. A trip valve device for air brakes, comprising a vent valve for controlling the discharge 01": air from the train pipe, trip mechanism for opening said valve, means normally tending to close the train pipe discharge, and latch mechanism normally subject to the train pipe pressure for term porarily holding said train pipe discharge open.

A trip valve device for air brakes, com. pnsing a vent valve and trip. mechanism for open ng same, a latch for locking said to close said mew-ea a valve open, and a. movable abutment normally subject to the train pipe pressure for releasing the latch.

10. A trip valve device for air brakes, comprising a. vent valve and trip mechanism for opening same, a latch for locking said valve open, and a piston subject to train pipe pressure for releasing the latch, said latch having an independent movement relative to the piston when the valve is 10 opened.

In testimony whereof I have hereunto set my hand.

EDWARD H. DEWSON.

Witnesses A. S. FOWLER, JAME M. HOGAN. 

